1. Field of the Invention
The invention relates in general to pushbuttons, and more specifically to pushbuttons having a key operable actuating plunger.
2. Description of the Prior Art
It is often necessary to limit access to a predetermined floor, or floors, of a building, such as an office building, to authorized personnel. For example, a floor housing a major computer system would be barred to the general public, but employees of this floor would be given some means to gain access. A convenient arrangement for providing restricted access to predetermined floors of a building is to employ key operated pushbuttons in the car call station of the elevator car, or cars, capable of serving the restricted floor, or floors.
A key operated pushbutton is generally a specifically constructed pushbutton, which is substituted as a complete assembly for the normal car call pushbutton. Copending application Ser. No. 941,617, filed Sept. 12, 1978, in the name of F. E. Coyle, entitled "Pushbutton Assembly", which is assigned to the same assignee as the present application discloses a new and improved pushbutton assembly which has many advantages for use as an elevator call pushbutton. The disclosed pushbutton is strong mechanically, and it will take misuse and abuse without damage to the electrical and mechanical components thereof. The housing includes an actuating plunger and legend blocks which identify a building floor. The cover carries all other components, including an electrical contact assembly and illuminating means. Assembly of the cover with the housing automatically operatively couples the actuating plunger with the electrical contact assembly, and it automatically aligns the illuminating means with the legend blocks. It would be desirable to add a key operable pushbutton option to the pushbutton assemblies constructed according to this concept.